A spunbond web is normally made by depositing fibers on a foraminous deposition belt. The fibers are often made of a thermoplastic synthetic resin. Generally and preferably, a suction device is provided under the foraminous deposition belt to draw air down through the foraminous deposition belt in the area where the fibers are deposited.
An apparatus of the type described above is known in practice in various embodiments. The foraminous deposition belt is usually guided over several rollers so that there is substantial contact between the roller surfaces and the deposition belt. Once the fibers are deposited on the foraminous deposition belt, some of them are sucked through the belt, e.g. between the warp and weft of the belt. These are termed “throughshots.”
The known apparatus has in the transfer area where the web is separated from the belt an output roller over which the deposition belt passes through a relatively large angle. In this output area, the spunbond web is usually transferred from the deposition belt to a calender in which it is compacted, so that the web moves off in its horizontal plane while the underlying belt pulls downward away from it as it moves around the output roller. As a result of the separation of the spunbond web from the belt, with the throughshot filaments passing through both, the bridging fibers are torn off, and the torn-off fibers are freed to go into the air as fiber waste (so-called “snow”). The fibers remaining between the warp and weft threads of the belt are pressed into and onto the belt due to the interaction of the belt with the rollers of the apparatus, thus forming undesired adhesion points for the spunbond web on the belt. This contamination of the belt has an adverse effect on the quality of the spun non-woven materials produced.